Field
This invention relates generally to a high-efficiency alternating channel counter-flow heat exchanger and, more particularly, to a heat exchanger configured with a matrix of separated hot fluid flow channels and cold fluid flow channels, where the hot channels and the cold channels alternate in each row and each column such that hot channels are adjacent only to cold channels and vice versa, and where the alternating channel counter-flow arrangement is enabled by channel-end flow blockers and a header/plenum for simplifying the plumbing of the hot and cold fluids.
Discussion
Heat exchangers have been used for decades to transfer heat energy from one fluid to another. In a typical application, a hot fluid is cooled by a secondary cool fluid. The hot fluid flows through a first passage, such as a tube or channel, and the cold fluid can either flow through a second passage or can flow freely over fins which are fixed to the first passage. The fluids can both be liquids, they can both be gases, or one can be a liquid and the other can be a gas, such as air.
In constrained-flow heat exchangers, where both fluids flow through channels or passages, there are three primary classifications of heat exchangers, according to their flow arrangement. In a cross-flow heat exchanger, the hot and cold fluids travel roughly perpendicular to one another through the heat exchanger. In parallel-flow heat exchangers, the two fluids enter the heat exchanger at the same end, and travel in parallel to one another to the other end. In counter-flow heat exchangers, the two fluids enter the heat exchanger from opposite ends. The counter-flow design is the most efficient, in that it can transfer the most heat between the fluids due to the fact that the average temperature difference along any unit length is greater.
One way of increasing heat exchanger efficiency is to increase the number of channels through which fluid flows, and decrease the size of the channels. Small channel size enables more complete transfer of heat energy from the hot fluid to the cold fluid for a given heat exchanger length. One heat exchanger design is essentially a cubic matrix of channels arranged in rows and columns, with the number of rows and columns in the hundreds, and the number of channels in the tens of thousands. In such a complex and intricate heat exchanger structure, although the efficiency benefits of a counter-flow arrangement would be desirable, it has not been possible or practical to fabricate such a design until now.